There is a problem that in the connection portion between a rare-earth-doped double clad fiber and a single mode fiber, pumping light leaks in a portion having the coating, and the fiber generates heat partially with this energy and deteriorates. Also, there is another problem that the output is limited as the oscillation wavelength becomes shorter. Accordingly, in a laser light source device formed by combining a fiber laser and a fiber amplifier, by using the residual pumping light in the fiber laser as the pumping light in the fiber amplifier, it is possible to enhance the reliability by preventing the fiber deterioration caused by the residual pumping light. Further, by amplifying the output in the fiber amplifier in the latter stage without any limitation on the pumping light output, it is possible to increase an output of the oscillation light.